London: Nigeria's oil minister and the head of Libya's state oil company are likely to attend a joint meeting between Opec and non-Opec nations on Friday, two Opec sources said, to discuss the progress of their deal to limit output.

Both countries are exempt from an Opec-led deal to cut output and their resulting boost to production has weighed on prices. This has prompted more talk about including Libya and Nigeria in the pact.

Nigerian oil minister Emmanuel Ibe Kachikwu is "most likely" to attend Friday's meeting, one of the sources said, while the second source said that Mustafa Sanalla, chairman of Libya's National Oil Corp, is also expected to join the meeting.

The Organisation of the Petroleum Exporting Countries (Opec) aims to clear a global oil supply glut by curbing output by about 1.2 million barrels per day, while Russia and other non-Opec producers are cutting half as much, until next March.

Ministers on a panel monitoring the deal, which comprises Kuwait, Venezuela and Algeria, plus non-Opec producers Russia and Oman, are scheduled to meet on Friday in Vienna.